import csv
import io
from flask import Blueprint, request, flash, redirect, url_for, session
from db import execute_db, get_db

data_imports_bp = Blueprint('data_imports', __name__)

def login_required_check():
    if 'user_id' not in session:
        return False
    return True

# --- ROUTE 1: Upload CURRENT Inventory (Global) ---
@data_imports_bp.route('/upload_current/<int:session_id>', methods=['POST'])
def upload_current(session_id):
    if not login_required_check(): return redirect(url_for('login'))
    
    if 'csv_file' not in request.files:
        flash('No file part', 'danger')
        return redirect(url_for('sessions.session_detail', session_id=session_id))
        
    file = request.files['csv_file']
    if file.filename == '':
        flash('No selected file', 'danger')
        return redirect(url_for('sessions.session_detail', session_id=session_id))

    if file:
        conn = get_db()
        cursor = conn.cursor()
        try:
            stream = io.StringIO(file.stream.read().decode("UTF8"), newline=None)
            csv_input = csv.DictReader(stream)
            
            # 1. Reset Table
            cursor.execute('DROP TABLE IF EXISTS BaselineInventory_Current')
            cursor.execute('''
                CREATE TABLE BaselineInventory_Current (
                    id INTEGER PRIMARY KEY AUTOINCREMENT,
                    item TEXT,
                    lot_number TEXT,
                    system_bin TEXT,
                    system_quantity REAL,
                    uom TEXT
                )
            ''')

            # 2. BULK INSERT with Correct Headers
            rows_to_insert = []
            for row in csv_input:
                # Clean up keys (remove hidden characters/spaces)
                row = {k.strip(): v for k, v in row.items()}
                
                rows_to_insert.append((
                    row.get('Item', ''), 
                    row.get('Lot Number', ''),  # FIX: Changed from 'Lot'
                    row.get('Bin Number', ''),  # FIX: Changed from 'Bin'
                    row.get('On Hand', 0),      # FIX: Changed from 'Qty'
                    row.get('UOM', 'LBS')
                ))

            cursor.executemany('''
                INSERT INTO BaselineInventory_Current 
                (item, lot_number, system_bin, system_quantity, uom)
                VALUES (?, ?, ?, ?, ?)
            ''', rows_to_insert)
            
            # 3. Update timestamp
            cursor.execute('UPDATE CountSessions SET current_baseline_timestamp = CURRENT_TIMESTAMP')
            
            conn.commit()
            flash(f'Successfully uploaded {len(rows_to_insert)} records.', 'success')
            
        except Exception as e:
            conn.rollback()
            flash(f'Error uploading CSV: {str(e)}', 'danger')
        finally:
            conn.close()
            
    return redirect(url_for('sessions.session_detail', session_id=session_id))

# --- ROUTE 2: Upload MASTER Baseline (Session Specific) ---
@data_imports_bp.route('/session/<int:session_id>/upload_master', methods=['POST'])
def upload_master(session_id):
    if not login_required_check(): return redirect(url_for('login'))
    
    if 'csv_file' not in request.files:
        flash('No file uploaded', 'danger')
        return redirect(url_for('sessions.session_detail', session_id=session_id))
    
    file = request.files['csv_file']
    if file.filename == '':
        flash('No file selected', 'danger')
        return redirect(url_for('sessions.session_detail', session_id=session_id))
    
    conn = get_db()
    cursor = conn.cursor()
    try:
        stream = io.StringIO(file.stream.read().decode("UTF8"), newline=None)
        csv_reader = csv.DictReader(stream)
        
        lot_location_data = {}
        
        # Consolidate duplicates in memory
        for row in csv_reader:
            # Clean keys here too just in case
            row = {k.strip(): v for k, v in row.items()}
            
            lot_num = row.get('Lot Number', '').strip()
            bin_num = row.get('Bin Number', '').strip()
            key = (lot_num, bin_num)
            
            # Use get() to handle potential missing keys gracefully
            qty = float(row.get('On Hand', 0))
            
            if key in lot_location_data:
                lot_location_data[key]['quantity'] += qty
            else:
                lot_location_data[key] = {
                    'item': row.get('Item', '').strip(),
                    'description': row.get('Description', '').strip(),
                    'location': row.get('Location', '').strip(),
                    'bin': bin_num,
                    'quantity': qty
                }
        
        # BULK INSERT
        rows_to_insert = []
        for (lot_num, bin_num), data in lot_location_data.items():
            rows_to_insert.append((
                session_id, 
                lot_num, 
                data['item'], 
                data['description'], 
                data['location'], 
                data['bin'], 
                data['quantity']
            ))

        cursor.executemany('''
            INSERT INTO BaselineInventory_Master 
            (session_id, lot_number, item, description, system_location, system_bin, system_quantity)
            VALUES (?, ?, ?, ?, ?, ?, ?)
        ''', rows_to_insert)
            
        cursor.execute('UPDATE CountSessions SET master_baseline_timestamp = CURRENT_TIMESTAMP WHERE session_id = ?', [session_id])
        conn.commit()
        flash(f'✅ MASTER baseline uploaded: {len(rows_to_insert)} records', 'success')

    except Exception as e:
        conn.rollback()
        flash(f'Error uploading Master CSV: {str(e)}', 'danger')
    finally:
        conn.close()

    return redirect(url_for('sessions.session_detail', session_id=session_id))